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Re-juvinate a NiCad Battery?
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nuckolls.bob(at)aeroelect
Guest

Posted: Thu Mar 08, 2012 1:16 pm Post subject: Re-juvinate a NiCad Battery?

At 10:27 AM 3/8/2012, you wrote:

 	  Quote: 	
		  Bob and others have mentioned trying the 3V/1Amp charge. What device 

or battery do you use to provide the 3V - 1Amp charge?


	


    There's nothing magic about either 3 volts or 1 amp. The task

    is to see if you can burn away any whiskers that have grown

    between the (+) and (-) plates to cause a short. I've used

    a D-size, Ni-Cad which has a considerable short circuit delivery

    characteristic. A computer grade, 200KuF electrolytic capacitor charged

    up with one or two alkaline cells (1.5 to 3 volts) can be a potent

    whisker blower. If you're successful in opening such faults,

    it will happen in milliseconds.

   Bob . . .

raymondj(at)frontiernet.n
Guest

Posted: Thu Mar 08, 2012 1:31 pm Post subject: Re-juvinate a NiCad Battery?

Noel mentioned he read an article indicating the 40-70% range as 

optimal.  I was hoping the same article might have told how to determine 

the charge state so the recommendations could be applied.



I use throw away batteries if I have a choice, but some of my tools only 

have rechargeable packs.  Doing what I can to maximize their life.



Thanks again,

Raymond Julian

Kettle River, MN



"And you know that I could have me a million more friends,

and all I'd have to lose is my point of view." - John Prine



On 03/08/2012 02:36 PM, Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   At 09:36 AM 3/8/2012, you wrote:

> 

>

> Is it voltage that is measured. Does the manufacturer supply a voltage

> vs. % charge graph or table? Or is it derived experimentally?

>

> I understand that there are cost/benefit issues here, but my objective

> is to understand the process from a physics perspective for my own

> education.



     Understand . . .

     I don't think that open circuit terminal voltage

     has a strong correlation to stored energy on the

     metal cells. Least wise, I've not seen any charts

     claiming to offer insight.



 Bob . . .



 *

 *

ainut(at)knology.net
Guest

Posted: Thu Mar 08, 2012 2:28 pm Post subject: Re-juvinate a NiCad Battery?

Also, be advised that some of the dirt cheap batteries (and even some 

full priced ones) are scams.  They hold very little battery material and 

last only a very short time.  Think of the batteries that "are included" 

with some of the cheap toys, for example.  Some of those have made it 

into the mainstream marketplace.  Caveat Emptor.



David M.

Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   

 <nuckolls.bob(at)aeroelectric.com>



 At 07:09 PM 3/6/2012, you wrote:

> 

>

> Question: How do you determine the percent charge on a battery pack. 

> Is it by voltage or current or what.  That's one of my pet peeves 

> with rechargeables in everything.  The batteries die from old age 

> rather than from reaching the max number of cycles.

>

> Looking forward to hearing about this.



    Okay, but you're probably not going to like it.

    Some years ago I wrote an article about the economics

    of using house branded AA cells in my airborne hardware.



 http://aeroelectric.com/articles/AA_Bat_Test.pdf



    The thrust of the article went to in-flight reliability

    of my battery powered hand held GPS and Comm radios

    coupled with risk mitigation. One night over west

    TX I found it necessary to change the four AA cells

<<<snip>>>

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Mar 08, 2012 10:47 pm Post subject: Re-juvinate a NiCad Battery?

At 03:55 PM 3/8/2012, you wrote:

 	  Quote: 	
		  



Also, be advised that some of the dirt cheap batteries (and even 

some full priced ones) are scams.  They hold very little battery 

material and last only a very short time.  Think of the batteries 

that "are included" with some of the cheap toys, for example.  Some 

of those have made it into the mainstream marketplace.  Caveat Emptor.


	


    Yeah . . . you can find Ni-Cd and Ni-Mh AA cells rated

    with over 2:1 differences in capacity.  It would be

    interesting to do the How Bad Can a Metal Battery Be?

    experiment on some of these cells.



    I've also noted that many so-called Ni-Cd "D" cells

    are a bit . . . shall we say . . . light? They

    are also rated in the 1500 to 2000 mAh range commensurate

    with a "C" cell. I think these batteries would be

    a disappointment too . . . a real Ni-Cad "D" is good

    for about 4000 mAh.



    The computer and DAS I used on the original battery

    killer experiments bit the dust a couple of years ago.

    I've got a new set of tools that I need to adapt to a

    battery box that holds at least 8 cells for testing at

    a time.



    I'm debating whether to stay with the original testing

    protocol for the AA alkaline cells that used a fixed

    resistor. Certainly good enough for comparative

    studies. I think I'd like to fit the test set with

    software controlled loads . . . probably power fets.

    This would let me run a wide range of discharge currents.

    It would also allow modulation of the test current

    during a discharge cycle to measure the cell's internal

    resistance. Dynamic loads would also let me discharge

    in a constant resistance, constant current or constant

    power modes. I need to talk to my software guy and see

    if he's up to making this hardware 'hum'. I'm not going

    to have time to do it for awhile.



    But you're quite right. What's marked on the label may

    not be all it claims to be.



   Bob . . .

rparigoris

Joined: 24 Nov 2009
Posts: 809

Posted: Fri Mar 09, 2012 4:26 am Post subject: Re-juvinate a NiCad Battery?

Hi Group 

 	A few notes on NiMh batteries: 

 	I've done quite a bit of testing on AA and AAA NiMh batteries lately and one theme that seems to ring true is by knowing the weight you can pretty much predict what sort of cell you have. I was running an average 50mA, 5 paralleled LED load (only 1 resistor) on three series AA batteries. It didn't matter if it was LSD or Non LSD, what ever the weight is of a Home Depot AA Energizer LSD cell, if you have about that weight you will get about 2100mAs of capacity. From Home Depot they are about 3$ each but if you shop hard on E-Bay you can get them for ~ 2$ each delivered. I purchased a half dozen different cells from E-Bay ranging from $.59 to $.79 each. Some have very beautiful packaging, but they all have written on them 3,000mA. After several C/10 for ~15 hour cycles they range in capacity from 600mAsa to ~900mAs with the 600s being lighter in weight than the 900s. Essentially the 600s are AAA "good stuff' squeezed into a AA wrapper. I also set up a fast discharge test and for the most part the lighter the cell the less ability it had to hold up to a high amp draw. That said I did test some Elite batteries that are Non-LSD cells that have the ability to dump amps at a much higher rate than the  Energizers. They claim they can take a 15 to 25 amp draw: http://www.cheapbatterypacks.com/product/122/Elite-2000-AA.aspx and it seems like the best AA NiMhs I've tested thus far as far as their ability to dump. I haven't flown a model with them, but suspect they will be pretty good at short bursts of 15 to 20 amps, pretty amazing. When you abuse cells beyond belief you want to see them stay above 1V for most of the cycle. They don't like to be fast peak charged though, best stay at 1C or 1.5C and you better have very low resistance connections and wires charging anything over ~ .75C (C being the Capacity of the battery). The capacity on the Elites is just ~ 2,000 mAs at my 50 mA draw where the Energizers are ~ 2100 mAs. BTW it's not a very good idea to take series NiMhs much below 1V. If the cells get out of balance and you have one that gets very discharged, the other cells are not going to do it any good for it's long life at all. With my 50mA load, there is very little capacity loft at 1V. If you test cells after you cycle them a few times, if you know the temperature and are using a 50mA load, then you can pretty easily tell if they are more or less than 75% charged. At room temp if you are seeing over 1.4 volts, you can be pretty sure you have over 90% capacity. If your over 1.35 volts then you are probably over 75%. Again this is with a 50mA load. Much below the 1.35 volt area it begins to get tricky. Different cells can be slightly higher or lower. There is a very long voltage hold out between ~ 1.2 and 1.35 volts so using voltage to figure out how much capacity is left will not be very accurate. Knowing if you are over 75% however is very useful! I forget the voltage, but once you see the voltage drop to ~ 1.15 volts, there isn't much capacity left. 

 	I set up a fast discharger to get cells quickly down to 1V with a 3 ohm resistor. I began with 3 paralleled 3 ohm, got to 1V, removed one 3 ohm resistor, got to 1V removed a second resistor, then got to 1V using only the one 3 ohm resistor and let it get to 1V. Now i have a known state of discharge. Using Bobs one LM1117 with a fixed resistor, three in parallel off a 12 volt battery, I can charge 6 AA cells in about 45 minutes on a timed charge. I cheat a little, I have 3 series for about the first half of the charge, then go down to 2, then complete with one. This is a low cost fast charger for third world countries. If they have the time a better way is to C/10 for 14 to 16 hours. With my fast charger I have it down where I get them 90 to 95% charged with very little chance of venting. Once a NiMh cell peaks, if you continue with a constant current charge the cells begin to warm up. With my pseudo 3 stage charge they barely get Luke warm at the end of the charge! BTW 1/2"  PVC tube works great as a AA holder. I did drill holes making it a piece of swiss cheese for cooling when fast charging, but you could probably get away with only two 1/4" holes per cell in case they vented. 

 	I built a pedal powered generator to charge up the 12volt battery that can use any bicycle, Home Depot 5 gallon buckets and a permanent magnet air conditioner blower motor for a car. I also top off my Odyssey PC545 aeroplane battery with it. The Odyssey is pretty amazing as far as it's ability to not self discharge.  If anyone is not totally bored here's some videos: 

 	http://communitysolutionsinitiative.org/2011/09/24/light-cycle-videos/ 

 	If anyone wants to make a pedal powered generator, here's step by step instructions: 

 	http://www.europaowners.org/main.php?g2_itemId=89553 

 	Pepboys PM102X permanent magnet motor costs $19.99 the last time I bought one. Some have tried PM102 either with nothing or a different letter at the end, and they may be reverse wound. They work OK you just need to reverse the wires. Using a Schottky diode prevents the motor from running off the battery and only loses a few percent to heat. I was using Rat Shack diodes until the Schottkys came in and they lose more to heat. 

 	One more thing, I love AstroFlight Whatt Meter (Whatt is correct): 	http://www.astroflight.com/index.php?main_page=index&cPath=2 

 	You can keep them alive with 4 NiMh or Alkaline batteries and measure down to and datalog even 1 cell. Expensive though. 

 	I fooled with these at half the price and as long as you can wait half of forever (they only build when they have enough orders): 

 	http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10080 

 	They are a pretty good value. They happen to have in stock at the moment! Probably not quite as accurate as the Astroflight though. 

 	Ron P.    [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Mar 09, 2012 6:40 am Post subject: Re-juvinate a NiCad Battery?

At 06:24 AM 3/9/2012, you wrote:



  	  Quote: 	
		  Hi Group



 A few notes on NiMh batteries:



 I've done quite a bit of testing on AA and AAA NiMh batteries lately and one theme that seems to ring true is by knowing the weight you can pretty much predict what sort of cell you have. 	


   <snip>



 

  	  Quote: 	
		  They are a pretty good value. They happen to have in stock at the moment! Probably not quite as accurate as the Astroflight though.



 Ron P. 	
  I'll add weight measurements to the gathered data on any future testing I do with the metal batteries. It probably wouldn't have been a useful data point with the AA alkaline cells . . . at the time I ran the first tests, there was little difference of significance in performance over the spectrum of products evaluated. I expect to see more differences in the metal world and weight may well be an important predictor. I do recall picking up a D cell that seemed too light and then observed that it was rated more like the family of C cells. At least they were honest about it.  



  Great data sir! I'm archiving this piece in my "battery performance" folder. When I update the AA battery article, I'd like to collaborate with you to add your findings to the knowledge base.

    Bob . . .    [quote][b]

ainut(at)knology.net
Guest

Posted: Fri Mar 09, 2012 7:00 am Post subject: Re-juvinate a NiCad Battery?

Along these battery lines, why can't we recharge these new lithium 

AA's?  That would cut battery buying to about a tenth...



David M.



Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   

 <nuckolls.bob(at)aeroelectric.com>



 At 03:55 PM 3/8/2012, you wrote:

> 

>

> Also, be advised that some of the dirt cheap batteries (and even some 

> full priced ones) are scams.  They hold very little battery material 

> and last only a very short time.  Think of the batteries that "are 

> included" with some of the cheap toys, for example.  Some of those 

> have made it into the mainstream marketplace.  Caveat Emptor.



    Yeah . . . you can find Ni-Cd and Ni-Mh AA cells rated

    with over 2:1 differences in capacity.  It would be

    interesting to do the How Bad Can a Metal Battery Be?

    experiment on some of these cells.



    I've also noted that many so-called Ni-Cd "D" cells

    are a bit . . . shall we say . . . light? They

    are also rated in the 1500 to 2000 mAh range commensurate

    with a "C" cell. I think these batteries would be

    a disappointment too . . . a real Ni-Cad "D" is good

    for about 4000 mAh.



    The computer and DAS I used on the original battery

    killer experiments bit the dust a couple of years ago.

    I've got a new set of tools that I need to adapt to a

    battery box that holds at least 8 cells for testing at

    a time.



    I'm debating whether to stay with the original testing

    protocol for the AA alkaline cells that used a fixed

    resistor. Certainly good enough for comparative

    studies. I think I'd like to fit the test set with

    software controlled loads . . . probably power fets.

    This would let me run a wide range of discharge currents.

    It would also allow modulation of the test current

    during a discharge cycle to measure the cell's internal

    resistance. Dynamic loads would also let me discharge

    in a constant resistance, constant current or constant

    power modes. I need to talk to my software guy and see

    if he's up to making this hardware 'hum'. I'm not going

    to have time to do it for awhile.



    But you're quite right. What's marked on the label may

    not be all it claims to be.



   Bob . . .




	


-- 

Tell the truth.  Be honest.  Be responsible to and for yourself.



We want our freedoms back.  Strike the illegal legislations called: 1) obamacare, 2) "Patriot (HA!) Act", and 3) 'presidential orders' that affect anyone besides gubmnt worker bees.

Hate crime laws?  Really?  Thought police?  Orwell would be proud.



Every gram of cocaine you buy from elsewhere contributes to an innocent being murdered in Central and South America.  Grow your own or Stop taking it.

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Mar 09, 2012 7:43 am Post subject: Re-juvinate a NiCad Battery?

At 08:31 AM 3/9/2012, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: David <ainut(at)knology.net>



 Along these battery lines, why can't we recharge these new lithium AA's?  That would cut battery buying to about a tenth...



 David M. 	
  For reasons similar to those that keep you from recharging say a Pink Bunny cell or a legacy carbon zinc cell. For a electro-chemistry system to be driven in reverse takes special attention to it's makeup. There ARE alkaline cells designed to be recharged. I've never used any but I've been curious about them. I may add them to the roster of test subjects.

  The short answer is that the designers of a given cell make adjustments to optimize the cell's performance characteristics in perhaps one or two features. Making a cell optimally rechargeable probably gives up some other performance feature.

  Bob . . .     [quote][b]

klehman(at)albedo.net
Guest

Posted: Fri Mar 09, 2012 11:00 am Post subject: Re-juvinate a NiCad Battery?

FWIW I've found rechargeable alkaline to be fine for low current devices 

such as remote controls. However after a couple of charges they are poor 

to non functional in anything that requires a bit of current such as a 

camera or anything with a motor in it. This experience is from perhaps 

20 AA cells over several years.

Ken



On 09/03/2012 10:42 AM, Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   At 08:31 AM 3/9/2012, you wrote:

> 

>

> Along these battery lines, why can't we recharge these new lithium

> AA's? That would cut battery buying to about a tenth...

>

> David M.



     For reasons similar to those that keep you from

     recharging say a Pink Bunny cell or a legacy carbon

     zinc cell. For a electro-chemistry system to be

     driven in reverse takes special attention to it's

     makeup. There ARE alkaline cells designed to be

     recharged. I've never used any but I've been curious

     about them. I may add them to the roster of test

     subjects.

     The short answer is that the designers of a given

     cell make adjustments to optimize the cell's performance

     characteristics in perhaps one or two features.

     Making a cell optimally rechargeable probably gives

     up some other performance feature.

     Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Mar 11, 2012 12:14 pm Post subject: Re-juvinate a NiCad Battery?

At 02:01 PM 3/9/2012, you wrote:

 	  Quote: 	
		  



FWIW I've found rechargeable alkaline to be fine for low current 

devices such as remote controls. However after a couple of charges 

they are poor to non functional in anything that requires a bit of 

current such as a camera or anything with a motor in it. This 

experience is from perhaps 20 AA cells over several years.


	


   Good data Ken. I'll get some numerical data

   on these too when I repeate the experiment.

   Bob . . .

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